Ecological evidence indicates a worldwide trend of dramatically decreased soil Ca2＋ levels caused by increased acid deposition and massive timber harvesting. Little is known about the genetic and cellular mechanism o...Ecological evidence indicates a worldwide trend of dramatically decreased soil Ca2＋ levels caused by increased acid deposition and massive timber harvesting. Little is known about the genetic and cellular mechanism of plants＇ responses to Ca2＋ depletion. In this study, transcriptional profiling analysis helped identify multiple extracellular Ca2＋ （[Ca2＋]ext） depletion-responsive genes in Arabidopsis thaliana L., many of which are involved in response to other environmental stresses. Interestingly, a group of genes encoding putative cytosolic Ca2＋ （[Ca2＋]cyt） sensors were significantly upregulated, implying that [Ca2＋]cyt has a role in sensing [Ca2＋]ext depletion. Consistent with this observation, [Ca2＋]ext depletion stimulated a transient rise in [Ca2＋]cyt that was negatively influenced by [K＋]ext, suggesting the involvement of a membrane potential-sensitive component. The [Ca2＋]cyt response to [Ca2＋]ext depletion was significantly desensitized after the initial treatment, which is typical of a receptor-mediated signaling event. The response was insensitive to an animal Ca2＋ sensor antagonist, but was suppressed by neomycin, an inhibitor of phospholipase C. Gd3＋, an inhibitor of Ca2＋ channels, suppressed the [Ca2＋]ext-triggered rise in [Ca2＋]cyt and downstream changes in gene expression. Taken together, this study demonstrates that [Ca2＋]cyt plays an important role in the putative receptor-mediated cellular and transcriptional response to [Ca2＋]ext depletion of plant cells.展开更多
基金supported by the Program for New Century Excellent Talents in University from the Ministry of Education (NCET-10-0906)the Major Basic Science Research Open Program from the Inner Mongolia Science and Technology DepartmentProgram for Innovative Research Team in Universities of Inner Mongolia Autonomous Region for Z. Qi
文摘Ecological evidence indicates a worldwide trend of dramatically decreased soil Ca2＋ levels caused by increased acid deposition and massive timber harvesting. Little is known about the genetic and cellular mechanism of plants＇ responses to Ca2＋ depletion. In this study, transcriptional profiling analysis helped identify multiple extracellular Ca2＋ （[Ca2＋]ext） depletion-responsive genes in Arabidopsis thaliana L., many of which are involved in response to other environmental stresses. Interestingly, a group of genes encoding putative cytosolic Ca2＋ （[Ca2＋]cyt） sensors were significantly upregulated, implying that [Ca2＋]cyt has a role in sensing [Ca2＋]ext depletion. Consistent with this observation, [Ca2＋]ext depletion stimulated a transient rise in [Ca2＋]cyt that was negatively influenced by [K＋]ext, suggesting the involvement of a membrane potential-sensitive component. The [Ca2＋]cyt response to [Ca2＋]ext depletion was significantly desensitized after the initial treatment, which is typical of a receptor-mediated signaling event. The response was insensitive to an animal Ca2＋ sensor antagonist, but was suppressed by neomycin, an inhibitor of phospholipase C. Gd3＋, an inhibitor of Ca2＋ channels, suppressed the [Ca2＋]ext-triggered rise in [Ca2＋]cyt and downstream changes in gene expression. Taken together, this study demonstrates that [Ca2＋]cyt plays an important role in the putative receptor-mediated cellular and transcriptional response to [Ca2＋]ext depletion of plant cells.
